Active control of supercooling degree using two surfactants of different molecular sizes

The authors have achieved active control of the supercooling degree by varying surfactant concentrations. To improve controllability of supercooling dissolution, the following experiments were carried out by different mixing methods using two kinds of surfactant of different molecular sizes. First, supercooling degrees were measured after dropping a “different” surfactant-pure water mixture with a fixed concentration onto a “base” surfactant-pure water mixture with a critical micelle concentration (CMC) in a glass test tube varying concentrations of the different surfactant-mixture. Second, supercooling degrees were measured after simultaneously mixing the mixture of a base surfactant at its CMC and a different surfactant of fixed concentration in a glass test tube varying the different surfactant-mixture concentrations. In both cases, adsorbed amounts of two surfactants to SiO2 surfaces were measured by a quartz crystal microbalance. Correlations among the mixing method, surfactant concentration of the total mixture, the supercooling degree and the adsorbed amount were clarified.